How do you move multiple faces by equal increments?
For symmetrical shapes the best method is to use array modifier.

Delete all the faces leaving only one cog then change to object mode and add an empty in the origin of the gear and rotate the empty 45 degrees.



Then add array modifier on the gear object, set count to 8, disable Relative Offset. Then enable Object Offset and select empty from the selection box and enable Merge and First and Last.



This way you can control the gear shape by modifying only on cog.